North Korea's newest threats were likely a response to the new US-South Korea agreement.

"We do not hide ... the strategic rocket forces are keeping within the scope of strike not only the bases of the puppet forces and the US. imperialist aggression forces' bases in the inviolable land of Korea but also Japan, Guam and the US. mainland," said an unidentified spokesman for North Korea's National Defence Commission, according to the Associated Press.

The US State Department refused to comment on the threat but said that the country was bound by UN resolutions to suspend its ballistic missile activity.

"Certainly rather than bragging about its missile capability, they ought to be feeding their own people," said State Department spokeswoman Victoria Nuland, according to Reuters.